How did past human populations respond to climate changes? We are interested in understanding how climate changes and, by extension, plant and faunal resources affected past human populations via the modification of their distribution area, demography, hunting-gathering strategies or producing innovations. We have been working on changes in the demography of Upper Paleolithic populations in Europe and on the replacement of Neanderthals by Anatomically Modern Humans. Recently, we are focusing on South African Middle Stone Age culture. This work is based on the compilation of archeological data from these two regions and the correlation with the palaeoclimatic sequences.